This invention relates to an improvement in a fastener for panels or the like, of the type comprising a bushing having a hollow shank that is inserted into holes in members such as panels to which the fastener is to be attached, and a pin having a shank that is inserted into the shank of the bushing.
One such fastener is disclosed in U.S. Pat. No. 4,276,806 (Patent Literature 1). Prior to use of this fastener, the pin and the bushing are connected by a thin piece to prevent loss of either part of the fastener. In use, the bushing shank can be inserted into an attachment hole in a first member and secured thereto preliminarily. Then, the bushing shank can be inserted into an attachment hole in a second member and secured thereto by the expansion of bushing parts beyond the diameter of the attachment hole in the second member. Insertion of the pin into the hollow bushing shank maintains a widened-diameter coupling condition in which the expansion of the bushing is maintained.
Japanese Laid-Open Utility Model Application No. S57-104007/1982, gazette publication (Patent Literature 2) discloses another pin-bushing type of fastener. With this fastener, the pin and the bushing are separate, and the pin shank is inserted into a hollow part of the bushing shank which has been inserted into attachment holes in a first member and a second member, so as to maintain a widened-diameter coupling condition in which the first and second members are coupled to one another. In an embodiment shown in FIG. 9(b) of this Patent Literature 2, there is a configuration in which the fastener can be coupled to the first member preliminarily.
Japanese Laid-Open Patent Application No. 2000-81012, gazette publication (Patent No. 2980897, gazette publication: Patent Literature 3) discloses a pin-bushing type of fastener wherein the pin and the bushing are separate as in Patent Literature 2. With this fastener also, the bushing can be pre-fastened to a first member, and then the bushing shank can be inserted into an attachment hole in a second member, and the pin completely pushed into the bushing to maintain a widened-diameter coupling condition.
Yet another pin-bushing type of fastener wherein the pin and bushing are separate is disclosed in Japanese Laid-Open Utility Model Application No. H6-69417/1994, gazette publication (Utility Model Registration No. 2581249: Patent Literature 4). With this fastener also, after the bushing has been inserted into attachment holes in first and second members, when the pin is inserted completely into the bushing shank, a widened-diameter coupling condition is maintained. In this fastener, there is no suggestion of pre-attaching the bushing to a first member, but there is a configuration wherein the pin and the bushing are coupled with the pin shank pushed part way into the bushing shank, so that neither of the pin and bushing is likely to be lost. In the condition wherein the pin is pushed part way into the bushing, the diameter of the bushing shank is not widened. Then by pushing the bushing shank into an attachment hole in a member and completely pushing the pin into the bushing, a widened-diameter coupling condition is maintained in which the first and second members are coupled to one another.
With the fasteners disclosed in Patent Literature 1 to 3 noted above, the fastener or the bushing can be pre-attached to a first member, so that when the bushing shank is inserted into a second member, a worker does not have to hold both the first member and the fastener separately, and the insertion operation is easily performed. However, with the fasteners described in Patent Literature 2 and Patent Literature 3, the pin and bushing are separate, and there is a danger of losing one or the other, which is undesirable. The fastener of Patent Literature 1 is formed so that, when not in use, the pin and bushing are coupled with a thin-material piece, so one or other of the parts will not be lost, but the thin-material piece breaks easily, and if it breaks due to a worker's mistake prior to use, the pin will be separated from the bushing, and there is a danger of one part being lost. With the fastener of Patent Literature 4, the pin and bushing are coupled in a non-widened-diameter coupling condition, so the danger of such loss is reduced. However, pre-attachment to a first member is not contemplated, so that when the bushing shank is inserted into a second member, the worker is obliged to hold both the first member and the fastener. This reduces efficiency in work flow on an automobile manufacturing line or the like, for example.